US4954903A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Digital signal reproduction apparatus for reading magneto-optical disks
Assignee: Sharp Corp
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Filing: 1988-09-19
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Granted: 1990-09-04
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Expires: 2008-09-19
Abstract
Abstract A digital signal reproduction apparatus includes a first differential circuit for differentiating a reproduction signal reproduced from a recording medium. This differential circuit outputs a first order differential signal and second differential circuit differentiates the first order differential signal of the reproduction signal and outputs a second order differential signal. A comparator compares the second order differential signal with a predetermined level to produce a window signal. A peak detecting circuit detects zero-cross points in the first order differential signal and outputs a peak detecting signal. A gate gates the peak detecting signal with the window signal to output a reproduction data signal.
Inventors
- 👤 Hiroshi Fuji
- 👤 Takeshi Yamaguchi
- 👤 Kunio Kojima
- 👤 Toshihisa Deguchi
- 👤 Shigeo Terashima
- 👤 Tsuneo Fujiwara
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 06:18
CPC Classifications
G; G11; G11B; G11B20/00; G11B20/10; G11B20/10009
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
208 words
A digital signal reproduction apparatus for reproducing data from a magneto-optical disk, comprising: comparative voltage generating means for generating a comparative voltage according to a reproduction signal reproduced from the magneto-optical disk; first comparing means, operatively connected to said comparative voltage generating means, for comparing said reproduction signal with said comparative voltage and for outputting a first window signal according to the comparison; first differential means, operatively connected to said first comparing means, for differentiating said reproduction signal and outputting a first order differential signal; second differential means, operatively connected to said first differential means, for differentiating said first order differential signal and outputting a second order differential signal; second comparing means, operatively connected to said second differential means, for comparing said second order differential signal with a predetermined level and outputting a second window signal according to the comparison; peak detecting means, operatively connected to said first differential means, for detecting a zero-cross point in said first order differential signal and outputting a peak detecting signal; and gate means, operatively connected to said peak detecting means and said first and second comparing means, for gating said peak detecting signal with said first and second window signals and outputting a reproduction data signal substantially without influence from noise.
Claim 2
Dependent Claim
208 words
A digital signal reproduction apparatus for reproducing data from a magneto-optical disk, comprising: comparative voltage generating means for generating a comparative voltage according to a reproduction signal reproduced from the magneto-optical disk; first comparing means, operatively connected to said comparative voltage generating means, for comparing said reproduction signal with said comparative voltage and for outputting a first window signal according to the comparison; first differential means, operatively connected to said first comparing means, for differentiating said reproduction signal and outputting a first order differential signal; second differential means, operatively connected to said first differential means, for differentiating said first order differential signal and outputting a second order differential signal; second comparing means, operatively connected to said second differential means, for comparing said second order differential signal with a predetermined level and outputting a second window signal according to the comparison; peak detecting means, operatively connected to said first differential means, for detecting a zero-cross point in said first order differential signal and outputting a peak detecting signal; and gate means, operatively connected to said peak detecting means and said first and second comparing means, for gating said peak detecting signal with said first and second window signals and outputting a reproduction data signal substantially without influence from noise.
Claim 3
Dependent Claim
42 words
The apparatus as claimed in claim 1, wherein said peak detecting means comprises a comparator for comparing said first order differential signal with a predetermined level and a trailing detecting circuit for detecting each trailing point of an output from said comparator.
Claim 4
Dependent Claim
39 words
The apparatus as claimed in claim 2, wherein said trailing detecting circuit comprises an inverter for inverting the delayed signal and a NOR gate for gating the delayed signal with the inverted signal to output a trailing detecting signal.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-09-03 | 1994-03-05 | 1994-09-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-09-03 | 1998-03-05 | 1998-09-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-09-03 | 2002-03-05 | 2002-09-04 | $7700.00 | Window Closed / Lapsed |